In the manufacture of electric lamps, such as mercury vapor lamps or metal halide lamps, which employ tungsten electrodes or lead-ins sealed in quartz arc tubes, a problem of "crazing" often causes rejects and consequent increased costs. The term "crazing" relates to cracks which form in the seal area. These cracks can weaken the seal and, in the worst case, cause loss of hermeticity. At least one cause for the "crazing" problem has been alleged to be the difference in the coefficients of thermal expansion between these two materials. The problem appears to be aggravated if the tungsten surface is smooth, such as is obtained by sinterless grinding of the tungsten.